The Science of Senescence

The average life expectancy has been steadily increasing over the centuries, from age 25 in prehistoric times, when the major killers were probably saber tooth tigers; to 40 at the end of the nineteenth century, when infectious diseases like diphtheria, tuberculosis and pneumonia took their toll; to 80 years today. Such an improving trend leads many to believe that the average life expectancy would continue to increase, if only we could eradicate the major killers of the industrialized world in the 21st century—cardiovascular disease, cancer and stroke. We know that it is humanly possible to live to age 122; Frenchwoman Jeanne Calment died at that ripe old age in 1997.

The topic of longevity has fascinated explorers since long before Ponce de Leon went looking for the fountain of youth. Today's explorations involve the study of genes and metabolic pathways...